Catalyst systems for Ziegler-Natta propene polymerisation

ABSTRACT

The invention relates to the use of nitrogenous aluminium organyl complexes of general formula (I) as co-catalysts in heterogeneous polymerisation reactions of propene. In said formula: R, R′, R 1  and R 1 ′ independently of one another represent branched or unbranched C 1 -C 7  alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl or alkynyl; R 2  represents unsubstituted, monoalkylated or polyalkylated and/or monofluorinated or polyfluorinated aromatic hydrocarbons from group (II); R 3  and R 4  independently of one another represent CH 2 , CF 2  oder C(R 1 ) 2 ; m stands for 0, 1 or 2; n stands for 0, 1 or 2; o stands for 0 or 1, all independently of one another. Said systems exhibit improved characteristics in terms of activity and stereoselectivity in comparison to conventional co-catalysts such as AlEt 3  and can act simultaneously as co-catalysts and stereoselectivity promoters

The present invention relates to the use of nitrogen-containingorganoaluminium complexes of the general formula (I)

in which

-   R, R′, R¹ and R¹′, independently of one another, are branched or    unbranched C₁-C₇-alkyl, -cycloalkyl, -alkenyl, -cycloalkenyl, -aryl    or -alkynyl;-   R² is an unsubstituted, mono- or polyalkylated and/or mono- or    polyfluorinated aromatic hydrocarbon from the group consisting of

-   R³ and R⁴, independently of one another, are CH₂, CF₂ or C(R¹)₂;    -   independently of one another-   m is 0, 1 or 2,-   n is 0, 1 or 2, and-   o is 0 or 1,    as cocatalysts in heterogeneous polymerisation reactions for the    polymerisation of propene. These systems have improved properties    with respect to activity and stereoselectivity compared with    cocatalysts conventionally employed, such as AlEt₃, and can at the    same time act as cocatalysts, but also as stereoselectivity    promoters.

Ziegler-Natta-catalysed polymerisation is a polymerisation process whichhas constantly been improved over a number of generations since theinitiating work by Ziegler and Natta in the 1950s. Increasing both theactivity and the stereoselectivity are the driving criteria for thecontinuous development of the catalyst system. The catalyst systems forthe polymerisation of 1-alkenes have in the meantime been divided intofive generations [E. Albizatti, U. Giannini, G. Collina, L. Noristi, L.Resconi, Polypropylene Handbook, E. P. Moore (Ed.), Hanser Publishers,Munich, 1996, 11].

Genera- Productivity^(a) Isotacticity Morphology tion Composition[kg_(pp)/g_(catalyst)] Index control 1. δ-TiCl₃0.33AlCl₃ + 0.8-1.2 90-94not possible AlEt₂Cl 2. δ-TiCl₃ + AlEt₂Cl 3-5 94-97 possible (10-15) 3.TiCl₄/ester/MgCl₂ +  5-10 90-95 possible AlR₃/ester (15-30) 4.TiCl₄/diester/ 10-25 95-99 possible MgCl₂ + (30-60) AlEt₃/silanes 5.TiCl₄/diether/ 25-35 95-99 possible MgCl₂ + AlEt₃  (70-120)^(a)Polymerisation: Hexane slurry, 70° C., 7 bar of propene, 4 hours, H₂for molecular weight regulation (values in parentheses originate frompolymerisations in bulk, 2 hours, 70° C., H₂).

The established system of today is based on the use of multicomponentcatalysts. In addition to the support material, these include, as theactual catalyst, a transition-metal compound, for example a titaniumcompound, which is first activated by addition of analuminium-containing cocatalyst. In addition, further constituents, suchas internal and external donors, are necessarily required. The use of aninternal donor here prevents agglomeration of the catalytically activespecies, while the external donor improves the stereospecificity on useof prochiral olefins. As can be seen from the table, a continuousimprovement process has taken place in recent decades, in which, up tothe fifth generation, in particular the surface areas of the supportedcatalysts have been increased and the proportion of a specificallyworking centres has been reduced [P. Pino, R. Mülhaupt, Angew. Chem.1980, 92 (11), 869; M. Boreo, M. Parrinello, S. Hüffer, H. Weiss, J. Am.Chem. Soc. 2000, 122, 501]. These catalyst systems save expensiveseparation of catalyst residues and complex extraction of atacticcomponents from the polyolefins prepared. The understanding that has nowbeen attained on the correlation between catalyst and polymer morphologyenables control of the polymer morphology during the polymerisationprocess, which eliminates additional processing steps, such as extrusionand granulation. Without the advances, solvent-free gas-phasepolymerisation and polymerisation in bulk would not have been possibleat all, and they have resulted in significant simplifications insuspension polymerisation [P. Galli, J. C. Haylock, Makromol. Chem.,Macromol. Symp. 1992, 63, 19-54; P. Corradini, V. Buscio, G. Guerra, inComprehensive Polymer Science, Vol. 4, G. Allen (Ed.), Pergamon Press,1989, p. 29; C. Jenny, P. Maddox, Solid State & Mat. Science 1998, 3,94; K. Soga, T. Shiono, Progress in Polymer Science 1997, 22, 1503].

The most important cocatalysts preferably used are alkylaluminiumcompounds, such as AlEt_(3 , Al-i-Bu) ₃, AlEt₂Cl, AlEtCl₂ and AlEt₂OR,all of which are very sensitive to atmospheric oxygen and moisture andare therefore difficult to handle. Besides the titanium chlorides,catalysts of interest are, in particular, compounds of vanadium andchromium, also molybdenum, cobalt, rhodium and nickel in specificapplications. Instead of the alkylaluminium compounds, numerous otherorganometallic compounds, in particular of sodium, lithium and cadmium,have been described as effective in combination with titanium compounds(H. J. Sinn et al., Polymerisation und Insertionsaktivität vonAluminium-trialkylen und Ziegler-Natta Katalysatoren [Polymerisation andInsertion Activity of Trialkylaluminium Compounds and Ziegler-NaftaCatalysts], Angew. Chem. 72 (1960) 522).

Besides achievement of the desired product properties, further factorsare crucial for assessment of the performance of a coordination catalystsystem, for the preparation of polymers, such as the activity of thecatalyst system, i.e. the amount of catalyst necessary for economicconversion of a prespecified amount of olefin, the product conversionper time unit and the product yield, the loss of catalyst and thereusability of the catalyst. There is therefore a demand for catalystsystems having the highest possible productivity, but also highspecificity in favour of a low degree of branching and highstereoregularity of the polymer.

Also essential, however, is the question of stability and handlingability of the catalyst or its components. Ingress of (atmospheric)oxygen and/or water reduces the activity of conventional catalysts orirreversibly destroys them. The catalysts therefore have to bestringently protected against the ingress of air and moisture duringpreparation, storage and use, which naturally makes handling moredifficult and increases the requisite effort.

Conventional catalyst systems are also sensitive to substancescontaining electron-rich elements, such as, for example, oxygen ornitrogen, in the molecule. Compounds such as ethers and amines, but alsopolar monomers which may be of interest as comonomers or additives forthe polymer, deactivate the catalyst.

Still more sensitive in this respect and therefore even more difficultto handle are the organometallic compounds to be employed as activatorsor cocatalysts, such as, in particular, the alkylaluminium compoundspredominantly used for this purpose. These very compounds represent aserious problem owing to their extreme sensitivity andself-combustibility in practice.

DE 19753135 has described a number of aluminium compounds which aredistinguished by an intramolecular donor side chain, for example anamino-, thio- or oxo-coordinated side chain, which can be prepared bymethods known to the person skilled in the art for the preparation oforganometallic compounds. These aluminium compounds act ascocatalytically activating components in Ziegler-Natta catalysts for thepolymerisation of ethylene. However, the polymerisation of propylene orhigher α-olefins does not succeed with the catalyst systems described inthis patent application. It was subsequently described in DE 10010796that the compounds described in DE 19753135 can be used for thepolymerisation of propylene if they are supported on MgCl₂ with additionof TiCl₄ or on use of MgCl₂/TiCl₄. However, the catalyst systems usedtherein do not achieve the productivities or activities obtained bymeans of conventional Ziegler-Natta catalyst systems (MgCl₂/TiCl₄AlEt₃).

The following factors were in need of improvement:

a) In order to be able further to increase the yield of polymers in thepolymerisation of propene, catalyst systems having higher activitieshave to be customised and developed. It should be possible to achievethe increase in activity by optimisation of the cocatalyst, since itconverts the catalyst into the species which is actually catalyticallyactive and continually reactivates it. This interaction between catalystand cocatalyst is crucial for the efficiency of the catalyst system as awhole.

b) The catalyst systems used on an industrial scale comprise highlypyrophoric, reactive, volatile alkylaluminium compounds as cocatalysts,in particular triethylaluminium. These compounds have high sensitivityto impurities in the reaction medium, such as, for example, to residualmoisture of the monomers to be polymerised. In addition, safe handlingof such highly pyrophoric and volatile compounds requires complex safetycontainers for their storage and for their transport with absoluteexclusion of oxygen and moisture. Furthermore, the industrial-scaleplants for catalyst preparation and polymerisation must be geared tothis problem. This is, in particular, a problem for industrially lessdeveloped countries and regions in which, owing to the climate, hightemperatures and high atmospheric humidity levels prevail.

c) In order to achieve high stereoselectivities in the Ziegler-Nattacatalysis of prochiral olefins, expensive external donors, such as, forexample, PhSi(OEt)₃, additionally have to be employed in many processes.It has hitherto not been possible to optimise to full satisfaction theproperties of the resultant polymers, which are determined, inter alia,by branching rates, tacticities, molecular weights and molecular-weightdistributions, which gives rise to a constant demand for polymers havingimproved, but also novel properties.

d) Since the cocatalyst in Ziegler-Natta catalysts is usually employedin high excesses to the catalyst and is thus the most expensivecomponent, there is great interest in reducing the cocatalyst/catalystratio while retaining the activity and stability of the catalyticallyactive species.

The object of the present invention is therefore to provide catalystsystems for the homopolymerisation of propene which do not have theproperties or disadvantages listed under a), b), c) and d). A furtherobject of the present invention was to provide in a simple andinexpensive manner corresponding catalyst systems which are bonded tosuitable supports. It should be possible to employ the catalyst systemsaccording to the invention in industrial-scale plants under simpleconditions with a lower cocatalysticatalyst ratio and at the same timethey should have higher activities than systems known hitherto. Afurther object of the present invention is to provide correspondingcatalyst systems which are less sensitive to impurities, in particularto moisture.

The object is achieved by the use of nitrogen-containing organoaluminiumcomplexes of the general formula (I)

in which

-   R, R′, R¹ and R¹′, independently of one another, are branched or    unbranched C₁-C₇-alkyl, -cycloalkyl, -alkenyl, -cycloalkenyl, -aryl    or -alkynyl;-   R² is an unsubstituted, mono- or polyalkylated and/or mono- or    polyfluorinated aromatic hydrocarbon from the group consisting of

-   R³ and R⁴, independently of one another, are CH₂, CF₂ or C(R¹)₂;    -   independently of one another-   m is 0, 1 or 2,-   n is 0, 1 or 2, and-   o is 0 or 1,    as components in coordination catalysts for the polymerisation of    propene.

Some of these specific compounds are novel, while others are describedin the literature. The use of these compounds for the polymerisation ofpropene is not described in the examples published by Patent ApplicationDE 19753135.

The object on which the invention is based is achieved, in particular,by the use of compounds of the general formula (I) in which

-   R, R′, R′ and R″, independently of one another, are branched or    unbranched C₁-C_(7 -alkyl,)-   R² is an unsubstituted hydrocarbon from the group consisting of

-   R³ and R⁴, independently of one another, are CH₂, CF₂ or C(R¹)₂; and-   independently of one another-   m is 0, 1 or 2,-   n is 0, 1 or 2, and-   o is 0 or 1.

From this group of compounds, those in which

-   R² is selected from the group consisting of

give particularly good results.

From this group of complexes, compounds of the general formula (I) inwhich

-   R¹ and R¹′ are CH₃ and-   R and R′, independently of one another, are i-C₃H₇, i-C₄H₉ or a    branched or unbranched alkyl from the group consisting of C₅H₁₁,    C₆H₁₃ and C₇H₁₅    have in turn proven particularly suitable for use as catalyst    component in the polymerisation of propene.

Equally suitable are also complexes

in which

-   R¹ and R¹′ are C₂H₅ and-   R and R′, independently of one another, are branched or unbranched    C₁-C₇-alkyl.

Particularly good results are achieved through the use ofnitrogen-containing organoaluminium complexes of the general formula (I)in which

-   R and R′, independently of one another, are CH₃, C₂H₅ or i-C₄H₉,-   R¹ and R¹′, independently of one another, are CH₃ or C₂H₅,-   R² is an unsubstituted hydrocarbon selected from the group    consisting of

-   R³ and R⁴ are CH₂, and m and n=0 or 1, and o=1.

Improved catalyst activities are preferably achieved using complexes ofthe general formula (I)

in which

-   R, R′, R¹ and R¹′, independently of one another, are branched or    unbranched C₁-C₇-alkyl,-   R² is

-   R³ is CH₂,-   m and o are 1, and-   n is 0.

Nitrogen-containing organoaluminium complexes of the general formula (I)

in which

-   R¹ and R¹′ are CH₃ and-   R and R′, independently of one another, are branched or unbranched    C₃-C₇-alkyl, or-   R¹ and R¹′ are C₂H₅ and-   R and R′, independently of one another, are branched or unbranched    C₁-C₇-alkyl,-   R² is

-   o is 1, and-   m and n are 0,    give comparable results.

Corresponding nitrogen-containing organoaluminium complexes can beemployed per se as cocatalysts in olefin polymerisation reactions.

It has been found that, in particular, compounds of the general formula

-   (I) selected from the group consisting of-   [3-(dimethylamino)propyl]dimethylaluminium,-   [3-(dimethylamino)propyl]diethylaluminium,-   [3-(dimethylamino)propyl]dipropylaluminium,-   [3-(dimethylamino)propyl]dibutylaluminium,-   [3-(diethylamino)propyl]dimethylaluminium,-   [3-(diethylamino)propyl]diethylaluminium,-   [3-(diethylamino)propyl]dipropylaluminium,-   [3-(diethylamino)propyl]dibutylaluminium,-   [4-(dimethylamino)butyl]dimethylaluminium-   [4-(dimethylamino)butyl]diethylaluminium-   [4-(dimethylamino)butyl]dipropylaluminium-   [4-(dimethylamino)butyl]dibutylaluminium-   [4-(diethylamino)butyl]dimethylaluminium-   [4-(diethylamino)butyl]diethylaluminium-   [2-(dimethylamino)phen-1-yl]dimethylaluminium,-   [2-(dimethylamino)phen-1-yl]diethylaluminium,-   [2-(dimethylamino)phen-1-yl]dipropylaluminium,-   [2-(dimethylamino)phen-1-yl]dibutylaluminium,-   [2-(diethylamino)phen-1-yl]dimethylaluminium,-   [2-(diethylamino)phen-1-yl]diethylaluminium,-   [2-(dimethylamino)benzyl]dimethylaluminium,-   [2-(dimethylamino)benzyl]diethylaluminium,-   [2-(dimethylamino)benzyl]dipropylaluminium,-   [2-(dimethylamino)benzyl]dibutylaluminium,-   [2-(diethylamino)benzyl]dimethylaluminium,-   [2-(diethylamino)benzyl]diethylaluminium,-   [2-(dimethylaminomethyl)phen-1-yl]dimethylaluminium,-   [2-(dimethylaminomethyl)phen-1-yl]diethylaluminium,-   [2-(dimethylaminomethyl)phen-1-yl]dipropylaluminium,-   [2-(dimethylaminomethyl)phen-1-yl]dibutylaluminium,-   [2-(diethylaminomethyl)phen-1-yl]dimethylaluminium,-   [2-(diethylaminomethyl)phen-1-yl]diethylaluminium,-   [2-(diethylaminomethyl)phen-1-yl]dipropylaluminium,-   [2-(diethylaminomethyl)phen-1-yl]dibutylaluminium,-   [8-(dimethylamino)naphth-1-yl]dimethylaluminium,-   [8-(dimethylamino)naphth-1-yl]diethylaluminium,-   [8-(dimethylamino)naphth-1-yl]dipropylaluminium and-   [8-(dimethylamino)naphth-1-yl]dibutylaluminium,    can be employed as components in coordination catalysts in propene    polymerisation reactions.

Experiments have shown that, in particular, the novel compounds selectedfrom the group consisting of

-   [2-(dimethylaminomethyl)phen-1-yl]dimethylaluminium,-   [2-(dimethylaminomethyl)phen-1-yl]diethylaluminium,-   [2-(diethylaminomethyl)phen-1-yl]diethylaluminium,-   [2-(dimethylamino)benzyl]diethylaluminium and-   [8-(dimethylamino)naphth-1-yl]dimethylaluminium    are suitable for this purpose and give very good polymerisation    results.

Compounds of the general formula (I) can therefore advantageously beemployed in accordance with the invention as components in coordinationcatalysts in heterogeneous propene polymerisation reactions.

The product properties can particularly advantageously be influenced bythe addition of these compounds since they can be employed specificallyas stereoselectivity promoters in the polymerisation of propene.

In accordance with the invention, the novel coordination catalysts forpolymerisation reactions comprise nitrogen-containing organo-aluminiumcomplexes of the general formula (I), in combination withtransition-metal compounds from sub-groups IV to VIII of the PeriodicTable of the Elements. These are preferably compounds selected from thegroup consisting of the halides of titanium and vanadium. Thesecompounds represent per se the actual catalysts in the polymerisationreaction.

In accordance with the invention, the nitrogen-containingorganoaluminium complexes of the general formula (I), can be used ascocatalysts in olefin polymerisation reactions.

This system consisting of coordination catalyst and catalyst is usuallybonded to a support material. The catalyst system according to theinvention is preferably bonded to an inorganic support selected from thegroup consisting of MgCl₂ and SiO₂, or mixtures thereof. The catalystsystem according to the invention may, if desired, comprise internaldonors, such as ether or ester compounds or such as, for example, ethylbenzoate, dimethyl phthalate or donors familiar to the person skilled inthe art, and, if desired, also external donors from the RSi(OR)₃ group,such as PhSi(OEt)₃, or external donors familiar to the person skilled inthe art.

The present invention relates, in particular, to the use of a catalystsystem of this type in heterogeneous propylene polymerisation reactions.

The nitrogen-containing organoaluminium complexes of the general formula(I) according to the invention can be employed in these reactions ascocatalyst and simultaneously also as stereoselectivity promoter. Thepolymer properties can be controlled through targeted selection of thecocatalyst. Surprisingly, it has been found that the molecular weightsof the polypropenes prepared using the cocatalysts according to theinvention are much higher than the molecular weights of the polypropenesprepared by means of AlEt₃. The nitrogen-containing organoaluminiumcomplexes according to the invention are thus particularly suitable forthe preparation of relatively high-molecular-weight polypropene.

The present invention furthermore relates to a process for thepreparation of catalyst systems according to the invention for thepolymerisation of propene.

Depending on the application, the catalyst systems can be prepared by

-   (a) supporting a titanium halide or vanadium halide on MgCl₂ or SiO₂    or on a combination of SiO₂ and MgCl₂, if desired with addition of    an internal donor, such as ether or ester compounds, such as ethyl    benzoate, dimethyl phthalate, or internal donors familiar to the    person skilled in the art, and, if desired, also external donors    from the RSi(OR)₃ group, such as PhSi(OEt)₃, or external donors    familiar to the person skilled in the art, and an organoaluminium    compound of the general formula (I),    or by-   (b) supporting an organoaluminium compound of the general    formula (I) on MgCl₂, SiO₂ or SiO₂ in combination with MgCl₂ and    addition of a titanium halide or vanadium halide and addition of an    internal donor, such as ether or ester compounds, such as ethyl    benzoate, dimethyl phthalate, or internal donors familiar to the    person skilled in the art, and, if desired, also external donors    from the RSi(OR)₃ group, such as PhSi(OEt)₃, or external donors    familiar to the person skilled in the art,    or by-   (c) supporting an active species generated from an organoaluminium    compound of the general formula (I) and a titanium halide or    vanadium halide on MgCl₂ or SiO₂ or on a combination of SiO₂ and    MgCl₂ with addition of an internal donor; such as ether or ester    compounds, such as ethyl benzoate, dimethyl phthalate, or internal    donors familiar to the person skilled in the art, and, if desired,    also external donors from the RSi(OR)₃ group, such as PhSi(OEt)₃, or    external donors familiar to the person skilled in the art.

Surprisingly, it has been found that on use of the nitrogen-containingorganoaluminium compounds of the general formula (I) in the presence ofa titanium halide or vanadium halide compound supported on magnesiumdichloride or SiO₂ or on a combination of SiO₂ and MgCl₂, if desiredalso with use of an internal donor, such as ether or ester compounds,such as ethyl benzoate, dimethyl phthalate, or internal donors familiarto the person skilled in the art, and, if desired, also external donorsfrom the RSi(OR)₃ group, such as PhSi(OEt)₃, or external donors familiarto the person skilled in the art, a catalyst system is formed which ishighly suitable for the polymerisation of propene and at the same timeenables yields which are substantially higher than those achieved by theconventional MgCl₂/TiCl₄/AlEt₃ comparative system. Various supportingmethods have been developed:

-   (a) supporting a titanium halide or vanadium halide on MgCl₂ or SiO₂    or on a combination of SiO₂ and MgCl₂ with addition of an internal    donor, such as ether or ester compounds, such as ethyl benzoate,    dimethyl phthalate, or internal donors familiar to the person    skilled in the art, and, if desired, also external donors from the    RSi(OR)₃ group, such as PhSi(OEt)₃, or external donors familiar to    the person skilled in the art, and addition of the    nitrogen-containing organoaluminium compound of the general formula    (I),-   (b) supporting the nitrogen-containing organoaluminium compound of    the general formula (I) on MgCl₂ or SiO₂ or on a combination of SiO₂    and MgCl₂ and addition of a titanium halide or vanadium halide and    addition of an internal donor, such as ether or ester compounds,    such as ethyl benzoate, dimethyl phthalate, or internal donors    familiar to the person skilled in the art, and, if desired, also    external donors from the RSi(OR)₃ group, such as PhSi(OEt)₃, or    external donors familiar to the person skilled in the art, and-   (c) supporting an active species already generated from the two    components on MgCl₂ or SiO₂ or on a combination of SiO₂ and MgCl₂    with addition of an internal donor, such as ether or ester    compounds, such as ethyl benzoate, dimethyl phthalate, or internal    donors familiar to the person skilled in the art, and, if desired,    also external donors from the RSi(OR)₃ group, such as PhSi(OEt)₃, or    external donors familiar to the person skilled in the art.

The experiments carried out have shown that method (a) gives the highestactivities during the polymerisation of propene. Virtually double theactivities can be obtained compared with the prior art. In particular,very high activities are obtained at low Al:Ti ratios; for example, theactivities at an Al:Ti ratio of 2:1 are a factor of 10-18 higher thanthe prior art. The experiments have furthermore shown that method (b)gives polypropenes having the highest pentad isotacticities. This showsthat the supported nitrogen-containing organoaluminium complexes of thegeneral formula (I) block titanium centres working aspecifically via thenitrogen atom. This positive effect does not occur in the nitrogen-freereference system AlEt₃.

It has been found that the properties of the polypropylenes can becontrolled through the choice of cocatalyst.

The catalyst systems according to the invention can advantageously beemployed under process-simplifying conditions. The latter is, inparticular, the case on use of a lower cocatalyst/catalyst ratio thanusual hitherto. The polymerisation properties can be controlled inaccordance with the invention by, in particular, a change in this ratio.

As a further advantageous property, it has been found that the novelcatalyst systems are fairly stable to air, moisture and impurities inthe reaction system and thus require technically less complex containersfor storage and transport or technically less complex plants forcatalyst preparation and for olefin polymerisation. The novel catalystsystems also have high thermal stability and a long service life underreaction conditions.

It has furthermore been found, surprisingly, that the novel catalystsystems consisting of MgCl₂ or SiO₂ or a combination of SiO₂ and MgCl₂,a titanium halide or vanadium halide compound, an internal donor and analuminium compound of the general formula (I) also act stereoselectivelyduring the polymerisation of propene without the addition of externaldonors.

The organoaluminium compounds of the general formula (I) can thussimultaneously take on a number of functions in the novel catalystsystems:

On the one hand, they act as cocatalysts and on the other hand, they actas stereoselectivity promoters. It is thus possible to reduce the numberof requisite catalyst components by one component. The third functionconsists in control of the molecular structure of the polymers, such asmolecular weights, molecular-weight distributions, tacticities andbranches, and thus of the polymer properties, such as hardness,rigidity, toughness, weldability, transparency, gas permeability andprocessability.

Besides the higher thermal stability and lower oxygen and moisturesensitivity found, a reduction in the number of catalyst componentsadditionally contributes to a general process simplification in catalystpreparation and propene polymerisation.

The low oxygen and moisture sensitivity of the aluminium compounds ofthe general formula (I), which facilitates easier and safer handling, isachieved by the intramolecular-stabilising amino group with coordinativestabilisation of the aluminium centre.

The nitrogen-containing organoaluminium complexes of the general formula(I) according to the invention

in which

-   R and R′, independently of one another, are CH₃, C₂H₅ or i-C₄H₅,-   R¹ and R¹′, independently of one another, are CH₃ or C₂H₅,-   R² is an unsubstituted hydrocarbon selected from the group    consisting of

-   R³ and R⁴ are CH₂,    and, independently of one another, m and n=0 or 1 and o=1,    can be prepared in a simple manner by    reacting a compound of the general formula (II)

in which R¹, R¹′, R², R³ and R⁴ are as defined above,with a compound of the general formula (III)

in which R and R′ are as defined above,in an aprotic solvent at a temperature in the range from −50 to +30° C.,and separating off the resultant reaction product. The reaction ispreferably carried out under a protective-gas atmosphere. Protectivegases which can be used here -are nitrogen gas or noble gases, such ashelium or argon. The starting materials are preferably employed in thereaction in an equimolar ratio to one another. Depending on thereactivity of the two reactants, however, it may also be appropriate toadd a compound of the general formula (III) in excess to the reactionmixture.

The aprotic solvents used for carrying out the reaction can be solventsselected from the group consisting of toluene, xylene, pentane,cyclopentane, hexane, cyclohexane and heptane, or mixtures thereof.

In order to achieve the most complete reaction possible, it isappropriate to stir the reaction mixture for some time without coolingafter the two reactants have been mixed at low temperature, during whichthe reaction mixture may warm to room temperature.

The reaction products formed by the reaction can be separated off and,if necessary, purified by methods known to the person skilled in theart.

The separation is preferably carried out by distillative methods. Theproducts are particularly preferably separated off by fractionaldistillation. Depending on the boiling point of the reaction productformed, this distillation is carried out under reduced pressure.

As described, the novel catalyst systems consist of support, catalyst,donor and cocatalyst:

The cocatalysts used are the nitrogen-stabilised organoaluminiumcompounds of the general formula (I), in which, independently of oneanother, three organyl groups are covalently bonded to the aluminiumatom. One of these organyl groups carries at the end an amino function,which is coordinatively bonded to the aluminium atom via the nitrogenatom, forming a cyclic structural unit. Two organyl substituents whichare independent of one another are bonded to the amino group. Theorganyl unit between the aluminium atom and the nitrogen atom caninclude, for example, a naphthyl, phenyl, benzyl or alkyl group, whichis unsubstituted or mono- or polyalkylated or -fluorinated. Preferenceis given to compounds which have an aromatic group in this organyl unit.

The catalysts used are transition-metal compounds from sub-groups IV toVIII of the Periodic Table of the Elements, in particulartransition-metal compounds from sub-groups IV and V of the PeriodicTable, in particular titanium halide and vanadium halide compounds.Suitable compounds are, for example, TiCl₄ and VCl₄.

The catalyst support used can be anhydrous MgCl₂ or SiO₂ or acombination of SiO₂ and MgCl₂.

The donors used are internal donors, such as ether or ester compounds,such as ethyl benzoate, dimethyl phthalate, or internal donors familiarto the person skilled in the art, and, if desired, also external donorsfrom the RSi(OR)₃ group, such as PhSi(OEt)₃, or other external donorsfamiliar to the person skilled in the art.

The supported catalyst systems according to the invention are preparedby a process which is disclosed with reference to examples given in thefollowing text. These examples represent specific embodiments. Theexpert knowledge of the person skilled in the art enables him to replacethe agents given therein by corresponding agents having the same action.

Solvents which can be used for the preparation of the supported catalystsystems are aprotic, nonpolar solvents, such as pentane, hexane,heptane, octane, benzene, toluene or xylene.

It has been found that effective systems are obtained if thecocatalyst/catalyst ratio is between 1:1 and 80:1, preferably between2:1 and 20:1.

It has been found that the use of the nitrogen-containingorganoaluminium compounds of the general formula (I) as cocatalysts inthe polymerisation of propene results in an increase in activity tovirtually double compared with the conventional catalyst systems on useof conventional Al:Ti ratios. In addition, the cocatalyst/catalyst ratioin the catalyst systems can be reduced to 1:1 or 2:1 without resultingin losses of activity. The activities obtained at these low Al:Ti ratiosare a factor of 10 to 18 higher than the activities obtained with AlEt₃.In this way, higher yields of polypropylene can be achieved, and theamount of cocatalyst in the catalyst systems can be drastically reduced.The catalyst systems according to the invention can thus be preparedsignificantly less expensively than corresponding systems known to date.It is possible to reduce the cocatalyst/catalyst ratio to values between5:1 and 1:1 without significantly influencing the yields and the targetquality of the products.

Polypropenes having significantly higher molecular weights of between200,000 and 800,000 g/mol are obtained.

The catalyst concentration is between 10⁻² and 10⁻⁶ mol/l, preferablybetween 10⁻³ and 10⁻⁵ mol/l.

The catalyst or cocatalyst loading on MgCl₂ is between 0.5 and 5 mmol/g,preferably between 1 and 3 mmol/g.

Due to their lower moisture and air sensitivity and due to their lowersensitivity to impurities during use in a polymerisation, the novelcatalyst systems enable safer handling and better reproducibility of theresults, but also higher long-term stability compared with the systemsof the prior art.

For better understanding and in order to illustrate the invention,examples are given below which are within the scope of protection of thepresent invention. However, owing to the general validity of theinventive principle described, these are not suitable for reducing thescope of protection of the present application merely to these examples.Furthermore, the contents of the cited patent application P 10010796should be regarded as part of the disclosure of the invention of thepresent description.

Examples of the Preparation of the Catalyst Systems:

a) Preparation of the Novel Cocatalysts:

[2-(Diethylaminomethyl)phen-1-yl]diethylaluminium

10.1 ml (88.54 mmol) of diethylaluminium chloride were added dropwise toa suspension, cooled to −10° C., of 14.98 g (88.54 mmol) of[2-(diethylaminomethyl)phen-1-yl]lithium in 130 ml of toluene in aninert nitrogen atmosphere (other inert gases, such as, for example,argon, are also suitable as protective gas). After slow warming to roomtemperature, the mixture was stirred for 16 hours in order to completethe reaction. Filtration through a D4 frit and removal of the solvent bydistillation gave 17.64 g of[2-(diethylaminomethyl)phen-1-yl]diethylaluminium (71.3 mmol/81%) as acolourless liquid by slow fractional distillation from the residue.

b.p.: 115° C./4·10⁻² mbar

¹H-NMR (C₆D₆, 200.1 MHz): δ 0.16-0.29 [m, 4H, Al(CHH′CH₃)₂]; 0.53 [t,³J=7.31 Hz, 6H, Al(CH₂CH₃)₂]; 1.40 [t, ³J=8.17 Hz, 6H, N(CH₂CH₃)₂];2.18-2.52 [m, 4H, N(CHH′CH₃)₂]; 3.34 (s, 2H, NCH₂); 6.68-6.91 (m, 1H,H_(ar)); 7.19-7.24 (m, 2H, H_(ar)); 7.88-7.93 (m, 1 H, H_(ar)).

¹³C-NMR (C₆D₆, 50.32 MHz): δ 0.3 [Al(CH_(2 CH) ₃)₂]; 8.1, 10.3[Al(CH_(2 CH) ₃)₂, N(CH₂CH₃)₂]; 44.2 [N(CH_(2 CH) ₃)₂]; 60.6 (NCH₂);123.7, 126.8, 127.2, 128.3, 137.4, 143.6 (C_(ar)).

²⁷ Al-NMR (C₆D₆, 104.3 MHz): δ 172.

[2-(Dimethylaminomethyl)phen-1-yl]diisobutylaluminium

20 ml (102.5 mmol) of diisobutylaluminium chloride were added dropwiseto a suspension, cooled to 0° C., of 15.36 g (108.8 mmol) of[2-(dimethylaminomethyl)phen-1-yl]lithium in 400 ml of pentane in aninert nitrogen atmosphere (other inert gases, such as, for example,argon, are also suitable as protective gas). After slow warming to roomtemperature, the mixture was stirred for 40 hours in order to completethe reaction. Filtration through a D4 frit and removal of the solvent bydistillation gave 23.94 g of[2-(dimethylaminomethyl)phen-1-yl]diisobutylaluminium (85%) as acolourless liquid by slow fractional distillation from the residue.

b.p.: 102-107° C./2·10⁻² mbar

¹H-NMR (C₆D₆, 200.1 MHz): δ 0.21 [2×dd, 4H, Al(CHH′)₂]; 1.21 [2×d, 12H,Al(CH₂CHCH₃CH₃′)₂]; 1.78 [s, 6H, N(CH₃)₂]; 2.09 [septet, 2 H,Al(CH₂CH)₂]; 3.17 (s, 2H, NCH₂); 6.85 (dd, 1H, C_(ar)H-3); 7.21 (m, 2 H,C_(ar)H-4.5); 7.91 (dd, 1H, C_(ar)H-6).

¹³C-NMR (C₆D₆, 50.32 MHz): δ 21.5 [broad, Al(CH₂ ₎ ₂]; 27.1[Al(CH_(2 CH)) ₂; 28.8 (AlCH₂CHCH₃CH₃′)₂]; 28.9 (AlCH₂CHCH₃CH₃′)₂]; 45.4[N(CH₃)₂]; 67.5 (NCH₂); 123.8 (CH_(ar)); 127.0 (CH_(ar)); 137.5(CH_(ar)); 143.5 (CH₂C_(ar)); 152.5 (very broad, AlC_(ar)).

²⁷ Al-NMR (C₆D₆, 104.3 MHz): δ 181.

[2-(Dimethylamino)benzyl]dimethylaluminium

10.0 ml (107.8 mmol) of dimethylaluminium chloride were added dropwiseto a suspension, cooled to −30° C., of 15.21 g (107.8 mmol) of[2-(dimethylamino)benzyl]lithium in 250 ml of hexane in an inertnitrogen atmosphere. After slow warming to room temperature, the mixturewas stirred for 14 hours in order to complete the reaction. Filtrationthrough a D4 frit and removal of the solvent by distillation gave 11.95g of [2-(dimethyl-amino)benzyl]dimethylaluminium (62.5 mmol/58%) as acolourless liquid by slow fractional distillation from the residue.

b.p.: 58° C./2·10⁻² mbar

¹H-NMR (C₆D₆, 200.1 MHz): δ 0.55 [s, 6H, Al(CH₃)₂]; 1.47 (s, 2H, AlCH₂);2.09 [s, 6H, N(CH₃)₂]; 6.58-6.63 (m, 1H, H_(ar)); 6.83-7.01 (m, 2H,H_(ar)); 7.26-7.30 (m, 1H, H_(ar)).

¹³C-NMR (C₆D₆, 50.32 MHz): δ 10.7 [Al(CH₃)₂]; 13.8 (AlCH₂); 46.3[N(CH₃)₂]; 118.0, 124.8, 127.4, 132.9, 143.0, 149.0 (C_(ar)).

²⁷ Al-NMR (C₆D₆, 104.3 MHz): δ 189.

[2-(Dimethylamino)benzyl]diethylaluminium

7.17 g (7.5 ml; 59.5 mmol) of diethylaluminium chloride were addeddropwise to a suspension, cooled to −30° C., of 8.40 g (59.5 mmol) of2-dimethylaminobenzyllithium in 150 ml of toluene in an inert nitrogenatmosphere. After slow warming to room temperature, the mixture wasstirred for 15 hours in order to complete the reaction. Filtrationthrough a D4 frit and removal of the solvent by distillation gave 8:05 gof [2-(dimethylamino)benzyl]-diethylaluminium (36.7 mmol/62%) as acolourless liquid by slow fractional distillation from the residue.

b.p.: 92° C./2·10⁻² mbar

¹H-NMR (C₆D₆; 200.1 MHz): δ-0.06-0.23 [m, 4H, Al(CHH′CH₃)₂]; 1.22 [t,³J=8.2 Hz, 6H, Al(CH₂CH₃)₂]; 1.45 (s, 2H, AlCH₂N); 2.14 [s, 6H,N(CH₃)₂]; 6.59-6.63 (m, 1H, H_(ar)); 6.82-7.00 (m, 2H, H_(ar));7.25-7.29 (m, 1H, H_(ar)).

¹³C-NMR (C₆D₆; 50.32 MHz): 6-0.8 [Al(CH_(2 CH) ₃)₂]; 9.9 [AlCH₂N]; 11.4[Al(CH_(2 CH) ₃)₂]; 46.3 [N(CH₃)₂]; 117.6; 124.7; 127.5; 132.9; 143.2;149.1 (C_(ar)). ²⁷ Al-NMR (C₆D₆; 104.3 MHz): δ 185.

[8-(Dimethylamino)naphth-1-yl]diisobutylaluminium

9.5 g (0.048 mmol) of diisobutylaluminium chloride were added dropwiseto a suspension, cooled to −40° C., of 12.1 g (0.048 mmol) of[8-(dimethylamino)naphth-1-yl]lithium etherate and 100 ml of diethylether in an inert nitrogen atmosphere. After slow warming to roomtemperature, the mixture was stirred for a further 24 hours in order tocomplete the reaction. Filtration through a D4 frit and removal of thesolvent by distillation gave 10.6 g of[8-(dimethylamino)naphth-1-yl]diisobutylaluminium (71%) as a colourless,oily liquid by fractional distillation from the residue.

b.p.: 147° C./10⁻² mbar

¹H-NMR (200.1 MHz, C₆D₆): δ 0.20 [ABX, 2H, ³J 6.9 Hz, ²J 14.0 Hz((CH₃)₂—CH—CHH′)₂Al]; d 0.36 [ABX, 2H, ³J 6.9 Hz, ²J 14.0 Hz((CH₃)₂—CH—CHH′)₂Al]; 1.18 [d, 12H, ³J 6.7 Hz, ((CH₃)₂—CH—CHH′)₂ Al];2.06 [m, ABX, 2H, ³J 6.7 Hz, ³J 6.9 Hz, ((CH₃)₂—CH—CHH′)₂Al]; 2.28 [s,6H, —N(CH₃)₂]; 6.74 (dd, ³J 7.5 Hz, ⁴J 1 Hz, 1H, H—C₇); 7.13 (dd, ³J 8.2Hz, ³J 7.5 Hz, 1H, H—C₆);); 7.47 (dd, ³J 8.2 Hz, ³J 6.2 Hz, 1H, H—C₃);7.55 (dd, ³J 8.2 Hz, ⁴J 1 Hz, 1H, H—C₅); 7.60 (dd, ³J 8.2 Hz, ⁴J 1.3 Hz,1H, H—C₄); 8.08 (dd, ³J 6.2 Hz, ⁴J 1.3 Hz, 1H, H—C₂).

¹³C-NMR (100.6 MHz, C₆D₆): δ 22.66 [broad, ((CH₃)₂—CH—CH₂)₂Al]; 27.12[(CH₃)₂—CH—CH₂)₂Al]; 28.85 [(CH₃)₂—CH—CH₂)₂Al]; 49.00 [—N(CH₃)₂]; 114.27(C₇); 124.73 (C₆); 125.92 (C₄); 127.81 (C₅); 127.86 (C₃); 133.61 (C₁₀);135.17 (C₂); 137.31 (C₉); 149.8 (very broad, C₁); 151.25 (C₈).

²⁷Al-NMR (104.3 MHz, C₆D₆): δ 195 (W_(1/2)=13.000 Hz).

b) Supporting of the Organoaluminium Complexes of the General Formula(I) on MgCl₂

-   Organoaluminium compound: n_(Al cocat)[mol]=m_(Al cocat)/M_(Al coat)-   MgCl₂: m_(MgCl2)=n_(Al cocat)/theor. loading    [mol(Al)/g]−m_(Al cocat)-   Hydrocarbon: for 3-8 g total amount (m_(MgCl2)+m_(Al cocat))50 ml

All work is carried out under a protective gas. The hydrocarbon used isdried and distilled before the reaction. The organoaluminium compoundand the magnesium chloride are introduced into a heat-dried flask withSchlenk attachment. The corresponding amounts are calculated from thedesired theoretical loading, which should be in the range 1-2*10⁻³ mol(Al)/g. Depending on the solubility of the organoaluminium compound,pentane, hexane, heptane, octane, benzene or toluene is added. Thereaction mixture is then stirred at room temperature for 12 hours. Thesolvent is subsequently removed under reduced pressure at 60-120 mbar.

The theoretical loading is calculated in accordance with the followingequation:(m _(Al cocat) /M _(Al cocat))/(m _(Al cocat) +m _(MgCl2))=theor.loading [mol(Al)/g]

Supported Loading Supported Loading component [mmol/g] component[mmol/g]

1.5

1.0Supporting of (3-dimethylaminopropyl)dimethylaluminium on MgCl₂

-   Al cocat: 1.77 g (1.2*10⁻² mol) M_(Al cocat)=143.21 g/mol

-   MgCl₂: 6.50 g (6.8*10⁻² mol) M_(MgCl2)=95.21 g/mol-   Pentane: 50 ml

All work was carried out under a protective gas. Pentane was dried anddistilled before the reaction. The organoaluminium compound and themagnesium chloride were introduced into a heat-dried 100 ml flask withSchlenk attachment. After addition of 50 ml of pentane, the reactionmixture was stirred at room temperature for 0.12 hours. The solvent wassubsequently removed for 2 hours under reduced pressure at 100-120 mbar,giving a pale-grey powder.

The theoretical loading was calculated in accordance with the followingequation:(m _(Al cocat) /M _(Al cocat))/(m _(Al cocat) +m _(MgCl2))=1.5*10⁻³mol/gc) Supporting of TiCl₄ on MgCl₂

Suspend MgCl₂ in 50 ml of pentane, add TiCl₄, stir for 12 hours at 25°C. under an inert-gas atmosphere, remove pentane at 80 mbar. Loading:1.4 mmol/g.

Examples of the Use of the Novel Catalyst Systems in the Polymerisationof Propene:

The polymerisation of propene is carried out continuously ordiscontinuously in a known manner by solution, suspension or gas-phasepolymerisation at a temperature of from 0° C. to +200° C., preferablybetween +20 and +140° C., and a pressure of from 1 to 20 bar, preferablyfrom 2 to 10 bar. The solvent used is hexane, heptane, octane, propeneor toluene.

The novel catalyst systems enable the preparation of homopolymers,copolymers and block polymers, preferably homopolymers, ofpolypropylene.

The activities of the catalyst systems in the polymerisation ofpropylene are higher than with the conventional catalyst systemcomprising MgCl₂, TiCl₄ and AlEt₃, even using a lowercocatalyst/catalyst ratio.

With all novel catalyst systems, finely particulate polymers wereobtained. The melting points and molecular weights of the polypropenesare in interesting ranges with respect to their industrial processing.

The polypropenes prepared using the nitrogen-stabilised organoaluminiumcompounds supported on MgCl₂ have higher pentad isotacticities than whenthey are used in dissolved form with MgCl₂/TiCl₄. In some cases, higherstereoselectivities are achieved than with AlEt₃ as cocatalyst. Thisresult may be caused by the effective blocking of aspecifically workingTi centres on the surface of MgCl₂ by means of the nitrogen-stabilisedorganoaluminium compounds.

Although higher stereoselectivities can be achieved with supportednitrogen-stabilised organoaluminium compounds, the polymerisation withMgCl₂/TiCl₄ and dissolved nitrogen-stabilised organoaluminium compoundsshould be given priority since it generally results in greateractivities.

The catalyst systems have a stereoselective action in the polymerisationof propylene without addition of donors. ¹³C-NMR analyses of thepolypropylene samples show linear structures with isotactic sequencelengths with a significantly higher frequently of the mmmm pentadscompared with AlEt₃. A further improvement in the stereoselectivitiescan be achieved through the use of donors.

Performance of the Polymerisation of Propylene

All polymerisations were carried out under an argon inert-gas atmosphereusing Schlenk techniques. The polymerisations were carried out in a 1 IBüchi glass autoclave. The reactor was evacuated for one hour in anoil-pump vacuum at 95° C. before each experiment and flushed a number oftimes with argon in the interim. The autoclave was filled successivelywith solvent and the supported cocatalyst suspended in solvent. Themonomer was then injected at the desired pressure. After saturation ofthe suspension located in the reactor with the monomer, thepolymerisation was initiated by injection of a solution of TiCl₄. In theexperiments with dissolved alkylaluminium compounds and supported TiCl₄,the addition of the catalyst suspension was carried out first. Thepolymerisations were then initiated by injection of a solution of thecocatalyst. Performance of the reaction at constant pressure was ensuredby the monomer supply to the reactor consisting of a pressure regulatorand a Brooks Instruments mass-flow regulator.

The polymerisations were terminated by injection of 5 ml of ethanol.Dilute hydrochloric acid was added to the polymerisation suspension,which was stirred overnight. The organic phase was neutralised usingsaturated sodium hydrogencarbonate solution and washed with water. Thesolvent was removed in an oil-pump vacuum to constant weight of thepolymer.

Polymer Analysis

The thermograms were recorded using a Meftler-Toledo 821e differentialcalorimeter at a heating rate of 20° C./min. The values obtained in the2nd heating phase were quoted as melting points.

The viscosity average molecular weights M_(η) were determined with theaid of an Ubbelohde viscometer. The samples were prepared by dissolvingabout 50 mg of the polymer in 50 ml of decahydronaphthalene. The flowtimes were measured by means of a LAUDA Viskoboy. The Mark-Houwinkconstants were taken from T. G. Scholte, N. L. J. Meijerink, H. M.Schoeffeleers, A. M. G. Brands, J. Appl. Polym. Sci. 29 (1984) 3763.

The ¹³C-NMR spectra were recorded using a BRUKER MSL 300 instrument.During the measurement, 1000 scans at a measurement frequency of 75.47MHz and a temperature of 100° C. were usually recorded. The pulse anglewas 60° and the relaxation delay was 6 seconds. The NMR samples wereprepared by making up a solution of 10 percent by weight of polymer in amixture of perchlorobutadiene and 1,1,2,2-tetrachlorodideuteroethane.

TABLE 1 Polymerisation of propylene using MgCl₂-supportedorganoaluminium compounds and TiCl₄ at 30° C. Activity[kg_(PP)/(mol_(Ti) T_(m) Crystallinity η M_(μ) Cocatalyst c_(propene)h)] [° C.] [%] [ml/g] [g/mol]

8 153 24 333 704,000 Comparison 62 152 12 217 388,000 AlEt₃Polymerisation conditions: T_(p) = 30° C., P_(monomer) = 2 bar, c_(Ti) =10⁻⁵ mol/l, Al/Ti = 5, t_(P) = 60 min.

TABLE 2 Microstructure of the polypropenes obtained using MgCl₂/organo-aluminium compounds and TiCl₄: Rel. Pentads int. rmrr + n_(iso) [%] mmmmmmmr rmmr mmrr mrmm mrmr rrrr rrrm mrrm

10 Rel.int.[%] 57.9 9.1 1.4 0.0 9.7 6.0 2.7 8.0 5.3 Comp. 7 Rel. 46.510.9 2.9 0.0 12.8 8.7 2.9 8.7 6.5 AlEt₃ int. [%]

TABLE 3 Polymerisation of propylene using MgCl₂/TiCl₄ andorganoaluminium compounds at 30° C. Activity [kg_(PP)/(mol_(Ti) T_(m)Crystal- M_(η) Cocatalyst c_(propene) h)] [° C.] linity [%] [g/mol]M_(w)/M_(n)

145 154 8 634,000 13.4

150 152 8 472,000 11.5 Comp. AlEt₃ 155 151 10 312,000 28.4Polymerisation conditions: T_(p) = 30° C. in toluene, P_(monomer) = 2bar, c_(Ti) = 10⁻⁵ mol/l, Al/Ti = 5

TABLE 4 The microstructure of the polypropenes obtained usingMgCl₂/TiCl₄ and organoaluminium compounds: Rel. Pentads int. rmrr +n_(iso) [%] mmmm mmmr rmmr mmrr mrmm mrmr rrrr rrrm mrrm

8 Rel.int.[%] 54.3 11.7 4.7 11.3 6.4 2.9 2.5 3.8 2.4

6 Rel.int.[%] 45.4 9.1 2.4 11.3 7.2 2.2 11.2 2.0 9.3 Comp. 7 Rel. 51.08.1 2.0 10.3 6.9 1.7 11.5 5.0 3.4 AlEt₃ int. [%]

FIG. 1 shows polymerisation results with the following variation of thepolymerisation temperature during the polymerisation of propylene usingMgCl₂/TiCl₄ and organoaluminium compounds at 2 bar.

Polymerisation conditions: Al/Ti=5, p_(propene)=2 bar, c_(Ti)=2.5·10⁻⁴mol/l in n-hexane, t_(P)=60 min.

FIG. 2 shows activity curves for the polymerisation of propene at 45° C.

TABLE 5 Properties of the polypropenes obtained Crystal- T_(P) T_(M)linity mmmm M_(η) Cocatalyst [° C.] [° C.] [%] [%] N_(iso) [g/mol]

304560 155156156 1011 9 34.937.940.8 455 438000475000406000

304560 156154155 111118 47.745.543.5 778 438000521000634000

60 157 27 40.0 5 360000 Comp. 30 153 12 37.6 5 247000 AlEt₃ 45 154 1644.0 6 215000 60 156 26 42.3 6 200000

TABLE 6 Variation of the Al/Ti ratio in the polymerisation of propyleneusing MgCl₂/TiCl₄ and organoaluminium compounds at 60° C. and 2 bar.Activity [kg/_(PP)/mol_(Ti)·h· mmmm T_(m) Crystallinity M_(η) CocatalystAl:Ti mol/l_(propene)] [%] [° ] [%] [g/mol]

 1.5 2 3 51020 223348319279203113 —3139455055 —154156156156157— 715161719 ——477000528000465000710000

 2 3 510 161297405339 29374145 154154155156  4 81214 —340000414000428000

 51020  0 5 55 —3026 —152152 — 5 2 —264000287000

 2 3 51020 218275320311295 3240454853 152153154154154  3 7121715—336000419000385000432000

 2 3 51020 295347312234120 3445475054 152153155156157  6 6101216—306000523000389000559000

 3 5102050  0 63 71 75 83 —23212226 —151151152152 — 1 1 3 6—233000249000—326000 AlEt₃  2  20 — — — —  3 269 28 152  2 243000  5 38040 153  8 191000 10 440 47 153 10 165000 20 456 54 155 18 218000 30 459— — — — 50 343 62 157 21 214000 Polymerisation conditions: T_(p) = 60°C. in n-hexane, p_(propene) = 2 bar, c_(Ti) = 2.5·10⁻⁴ mol/l, t_(P) = 60min.

FIG. 3 shows the variation of the Al/Ti ratio in the polymerisation ofpropylene using MgCl₂/TiCl₄ and organoaluminium compounds at 60° C. and6 bar.

Polymerisation conditions: T_(p)=60° C. in n-hexane, P_(propene)=6 bar,x_(Ti)=5·10⁻⁴ mol/l, t_(P)=60 min.

TABLE 7 Melting points and crystallinities of the polypropenes obtainedT_(m) [° C.] Crystallinity [%] Al/Tiratio

T_(m) [° C.]AlEt₃

Crystallinity[%] AlEt₃ 1 153 — 10 — 3 154 147 14 7 5 156 153 25 18 10156 153 22 20 25 156 151 17 6 50 157 153 30 21 100 156 — 38 —

1. A nitrogen-containing organoaluminium complex of formula (I)

in which (1) R¹ and R¹′ are CH₃, R and R′, independently of one another,are branched or unbranched C₃₋₇-alkyl, R² is

R³ CH₂, m and o are 1, and n=0; (2) R¹ and R¹′ are C₂H₅, R and R′,independently of one another, are branched or unbranched C₁-C₇-alkyl, R²is

CH₂, m and o =1, and n =o; (3) R, R′, R¹ and R¹′, independently of oneanother, are branched or unbranched C₁-C₇-alkyl, R² is

R⁴ is CH₂, n and o are 1, and m is 0; or (4) R¹ and R¹′ are CH₃, R andR′, independently of one another, are branched or unbranchedC₃-C₇-alkyl, or R¹ and R¹′ are C₂H₅ and R and R′, independently of oneanother, are branched or unbranched C₁-C₇-alkyl, R² is

o is 1, and m and n are
 0. 2. A nitrogen-containing organoaluminiumcomplex according to claim 1 of formula (I) (1) in which R¹ and R¹′ areCH₃ and R and R′, independently of one another, are i-C₃H₇, i-C₄H₉ or abranched or unbranched alkyl from the group consisting of C₅H₁₁, C₆H₁₃and C₇H₁₅.
 3. A nitrogen-containing organoaluminium complex according toclaim 1 of formula (I) (2) in which R¹ R¹′ are C₂H₅ and R and R′,independently of one another, are CH₃, C₂H₅ or i-C₄H₉.
 4. A coordinationcatalyst system comprising a nitrogen-containing organoaluminium complexof formula (I) according to claim 1 in combination with atransition-metal compound from sub-groups 4 to 10 of the Periodic Tableof the Elements.
 5. A coordination catalyst system according to claim 4comprising halides of titanium or vanadium.
 6. A coordination catalystsystem according to claim 4 bonded to an inorganic support comprisingMgCl₂, SiO₂, or mixtures thereof.
 7. A coordination catalyst systemaccording to claim 4, further comprising internal electron donors whichare ethers or esters, and, optionally an, external electron donorRSi(OR)₃ which is PhSi(OEt)₃.
 8. A process for the preparation ofpolypropylene, comprising polymerizing propene under polymerizationconditions in the presence of a nitrogen-containing organoaluminiumcomplex of formula (I) according to claim
 1. 9. A process for thepreparation of nitrogen-containing organoaluminium complexes of formula(I) according to claim 1 comprising reacting a compound of formula (II)

with a compound of formula (III)

in an aprotic solvent at a temperature in the range from −50 to +30° C.,and optionally separating the resultant reaction product.
 10. A processaccording to claim 9, wherein the aprotic solvent is toluene, xylene,pentane, cyclopentane, hexane, cyclohexane, heptane, or mixturesthereof.
 11. A process according to claim 9, wherein the reactionproduct formed is separated off by distillation.
 12. A process for thepreparation of polypropylene, comprising polymerizing propene underpolymerization conditions in the presence of a coordination catalystsystem according to claim
 4. 13. A process for the preparation of acatalyst system for the polymerisation of propene, comprising (a)supporting a titanium halide or vanadium halide on MgCl₂ or SiO₂ or on acombination of SiO₂ and MgCl₂, optionally with addition of an internaldonor, and an organoaluminium compound of formula (I) according to claim1 or (b) supporting an organoaluminium compound of formula (I) on MgCl₂,SiO₂ or SiO₂ in combination with MgCl₂, and adding a titanium halide orvanadium halide, and adding an internal donor and/or external donor, or(c) generating an active species from an organoaluminium compound offormula (I) and a titanium halide or vanadium halide, and this specieson MgCl₂ or SiO₂ or on a combination of SiO₂ and MgCl₂ with addition ofone or more internal electron donors and, optionally, one or moreexternal electron donors.
 14. A process according to claim 13, whereinthe supporting is carried out in aprotic, nonpolar solvents.
 15. Aprocess according to claim 14, wherein the aprotic, nonpolar solventsare pentane, hexane, heptane, octane, benzene or toluene.
 16. A processaccording to claim 13, wherein the internal electron donors are ethylbenzoate, or dimethyl phthalate, and the external electron donor isPhSi(OEt)₃.